Practice Prevention Perchlorate

“The thyroid from the Learning and Developmental Disabilities Initiative gland February 2007 produces several hormones What is perchlorate? essential for regulating our Perchlorate is a chemical that occurs in nature but is also body’s manufactured for industrial products and processes. It is metabolism. used mostly in explosives and rocket propellants for These munitions (mortars, grenades, flares and solid rocket fuel). hormones are Perchlorate is also used in smaller quantities in fireworks, absolutely blasting agents, matches, lubricating oils, nuclear reactors, critical to the 1 development air bags and certain types of fertilizers, as well as in of the fetal tanning and leather finishing, rubber manufacture and paint 2 brain and nervous system. Fetal brain and enamel production. development begins within the first several weeks of gestation. The fetus’ thyroid gland does Perchlorate residues are being found with increasing not begin to work until the third trimester of frequency in water, soils and even foods. Perchlorate is pregnancy. Thus, it is essential that the mother known as a persistent toxicant and can remain in water and produce adequate amounts of these hormones soils for long periods. so that the fetus will have the levels it needs. Even a small disruption in a mother’s hormone level at critical stages in brain development can How does perchlorate interfere with the have long-term, and sometimes devastating, development of a child’s brain and nervous impacts on a child’s health. system? Perchlorate is a chemical that occurs in nature but is also man-made. It is used in explosives The thyroid gland produces hormones that regulate and rocket propellants as well as in air bags, metabolism in adults. These hormones also help control the certain types of fertilizers, and other products. growth and development of a child’s body, including the Perchlorate residues are also found with brain and nervous system. If a pregnant woman’s thyroid increasing frequency in water, soils, and food. gland isn’t producing enough thyroid hormone, her child Perchlorate can impact thyroid hormone may show changes in behavior, delayed development and production. It prevents iodide uptake into the difficulty in learning.1,3 Pregnant women with low thyroid thyroid gland, resulting in a reduced production function also have a much higher risk of medical problems of thyroid hormones. This article explains ways during pregnancy and premature birth, further putting their to reduce the risks of perchlorate exposure. The children’s health and development at risk.4 Please see our best prevention, however, is to be sure that a related columns on “The Thyroid Gland” and “Iodine and woman who is pregnant or who might become Thyroid Function” for more information. pregnant not be in a low-thyroid, or hypothyroid, condition. For this reason, I recommend that any One study tested the children of women who had low levels woman have a thyroid function test done before of thyroid hormone and did not receive thyroid treatment a planned pregnancy or as soon as a she during pregnancy. When the children were seven to eight realizes she is pregnant. Preventing a hypothyroid condition will minimize or prevent years old, they were given 15 tests of intelligence, any impacts on fetal brain development. Please attention, language, reading ability, school performance, read this article for more information.“ and visual-motor performance. These children scored slightly lower on all tests, and their IQ scores were seven - Larry B. Silver, MD points lower on average compared to children of women Page 2 Perchlorate with normal hormone levels.3 deficiency is of special concern.6,7 A study published by the Centers for Disease Control (CDC) Perchlorate prevents iodide uptake into the thyroid 5 in 2006 found that even very low levels of gland, interfering with its production of hormones. perchlorate in a woman’s body are related to low About 2.5% of women have a low thyroid hormone thyroid hormone production.8 condition in which the thyroid gland produces less hormone than normal. When severe, this condition Young children, whose thyroid glands are still is known as hypothyroidism. Because there may be developing, may also be at greater risk from no symptoms with mild hypothyroidism (called perchlorate exposures. Because the brain subclinical hypothyroidism), most women with this continues to grow and develop through condition are not aware of it and do not receive any adolescence, a child’s healthy thyroid function is treatment. There are also some women who do not important. Only minimal research on the effects of receive the recommended daily amounts of iodine perchlorate exposure on young children has been in their diets. Without enough iodine, the thyroid conducted, but because of its effects in animal gland cannot make an adequate supply of thyroid studies, perchlorate is a concern and warrants hormone. The effects of exposure to perchlorate in further study.9 these women with hypothyroidism or iodide

How are children exposed to perchlorate?

Most exposures to perchlorate come from drinking water at concentrations of 4 parts per billion or contaminated water. Water can be contaminated higher.6 during perchlorate manufacture or through improper storage or disposal of materials containing Food can also contain perchlorate if it was grown in perchlorate.1 Environmental releases of perchlorate contaminated soil or irrigated or processed with have been discovered in at least 35 states contaminated water. Various levels of perchlorate have been found in lettuce, milk, and bottled water, throughout the United States, and more than 11 5 million people have perchlorate in their drinking and more foods are being tested for perchlorate.

What can you do to reduce your child's risk?

Ask your doctor for a thyroid test. Pregnant per kilogram of body weight should not threaten the women, or those who are likely to become health of even the most sensitive populations. This pregnant, are highly encouraged to be screened for translates to 24.5 parts per billion in drinking water thyroid functioning. Since a thyroid test is not for adults. However, this level does not consider automatically ordered by most doctors, women additional daily perchlorate exposures from other need to ask for testing and for treatment if needed. sources such as food,10 nor does it consider that Once detected, hypothyroidism can easily be babies consume six times the amount of fluid as corrected with low-cost, daily medication. adults for their weight, so the level in water may need to be lowered substantially for pregnant Ask government authorities to install a treatment women, babies and young children. In 2006 system for your community or purchase a home Massachusetts adopted a standard of two parts per treatment system. Water treatment systems, either billion in drinking water,11 based on the 2006 CDC for whole cities or for home use, can remove report.8 perchlorate from water supplies. Based on a report by the National Academy of Sciences,6 the Avoid food grown in contaminated areas. Environmental Protection Agency has concluded Unfortunately, there is no easy way to tell if food is that exposure of 0.0007 milligrams of perchlorate contaminated with perchlorate. Even organically Practice Prevention Page 3 grown produce may have perchlorate levels above irrigated by perchlorate-contaminated water, such those recommended by the EPA. Parents can avoid as central California or areas that use Colorado purchasing food from areas that are known to be River water.12

Footnoted resources 1. US Environmental Protection Agency. Federal http://books.nap.edu/execsumm_pdf/11202.pdf, viewed Facilities Restoration and Reuse: Perchlorate. February 2, 2007. www.epa.gov/fedfac/documents/perchlorate.htm, viewed 7. Madsen T, Kucher Y, Olle T. Growing Up Toxic: April 21, 2005. Chemical Exposures and Increases in Developmental 2. US Food and Drug Administration. Exploratory Data Disease. June 2004. www.environmentcalifornia.org/ on Perchlorate in Food. reports/GrowingUpToxic2004.pdf, viewed June 3, 2005. www.cfsan.fda.gov/~dms/clo4data.html, viewed April 21, 8. Blount BC, Pirkle JL, Osterloh JD, Valentin-Blasini L, 2005. Caldwell KL. Urinary perchlorate and thyroid hormone 3. Haddow JE, Palomaki GE, Allan WC, Williams JR, levels in adolescent and adult men and women living in Knight GJ, Gagnon J, O'Heir CE, Mitchell ML, Hermos the United States. Environmental Health Perspectives. RJ, Waisbren SE, Faix JD, Klein RZ. Maternal thyroid 2006 Dec;114(12):1865-71. deficiency during pregnancy and subsequent 9. The American Thyroid Association. ATA Public Health neuropsychological development of the child. New Committee Statement: The Question of Perchlorate England Journal of Medicine. 1999 Aug 19;341(8):549- Exposure and Potential Effects on the Thyroid. 55. www.thyroid.org/professionals/publications/statements/0 4. Casey BM, Dashe JS, Wells CE, McIntire DD, Byrd W, 4_02_03_perchlorate.html, viewed May 9, 2005. Leveno KJ, Cunningham FG. Subclinical hypothyroidism 10. Walker B. Rocket Fuel in Drinking Water. and pregnancy outcomes. Obstetrics and Gynecology. www.faultline.org/news/2003/03/perc.htm, viewed June 2005 Feb;105(2):239-45. 3, 2005. 5. US Food and Drug Administration Center for Food 11. Standard needs to be realistic. Ontario Daily Bulletin. Safety and Applied Nutrition. Perchlorate Questions and January 22, 2007. www.dailybulletin.com/search/ Answers. www.cfsan.fda.gov/~dms/clo4qa.html, viewed ci_5058486, viewed February 1, 2007. April 21, 2005. 12. Perchlorate contamination of U.S. lettuce crop. 6. Committee to Assess the Health Implications of www.freedrinkingwater.com/water-pollution-perchlorate- Perchlorate Ingestion, National Research Council. Health lettuce.htm, viewed June 3, 2005. Implications of Perchlorate Ingestion (Free Executive Summary). National Academies Press.

This and other Practice Prevention columns are written and For more published by LDDI staff at the Collaborative on Health and the information or for Environment, with an introduction provided by LDDI Medical other Practice Advisor Dr. Larry B. Silver. Dr. Silver is a child and adolescent Prevention psychiatrist and clinical professor of psychiatry at Georgetown columns, visit the University Medical Center. He has published several popular books Learning and for parents, educators and clinicians about learning disabilities, Developmental Disabilities attention deficit hyperactivity disorder, health and mental health. Past Initiative online at president of the Learning Disabilities Association of America, he www.disabilityandenvironment.org received their Learning Disabilities Association Award. He also or call 360-331-7904. received the Berman Lifetime Achievement Award from the American Academy of Child and Adolescent Psychiatry for his contributions to the study and treatment of learning disabilities. More information about Dr. Silver is available on the LDDI website: www.healthandenvironment.org/initiatives/learning/r/prevention.